Changes in bacterial communities from swine feces during continuous culture with starch

Bacteria from swine feces were grown in continuous culture with starch as the sole carbohydrate in order to monitor changes during fermentation and to determine how similar fermenter communities were to each other. DNA extracted from fermenter samples was analyzed by denaturing gradient gel electrophoresis (DGGE). A significant decrease in diversity was observed, the Shannon-Weaver index dropped from 1.92 to 1.13 after 14 days of fermentation. Likewise, similarity of fermenter communities to those in the fecal inoculum also decreased over time. Both diversity and similarity to the inoculum decreased most rapidly in the first few days of fermentation, reflecting a period of adaptation. Sequencing of DGGE bands indicated that the same species were present in replicate fermenters. Most of these bacteria were placed in the Clostridium coccoides/Eubacterium rectale group (likely saccharolytic butyrate producers), a dominant bacterial group in the intestinal tract of pigs. DGGE proved useful to monitor swine fecal communities in vitro and indicated the selection and maintenance of native swine intestinal bacteria during continuous culture.